(771c) Strong Electrostatic Adsorption for the Facile Synthesis of Supported, Dilute Limit Alloy Nanoparticles

Recent catalyst design takes advantage of the active sites formed by having a single atom on a supported metal surface to create a single atom or dilute limit alloy catalyst. This category of well dispersed atoms alloyed on a metal surface have shown unique functionality for reactions like selective hydrogenation of alkynes and dienes to alkenes, ethanol dehydrogentation, and the Ullmann reaction of aryl chlorides [1], [2]. Flytzani-Stephanopulos prepared such nanoparticles on an alumina support via galvanic displacement of Cu by Pd [3]. This method is limited to only those systems which possess the correct reduction potentials. In the current work, we present a generalizable method to prepare an infinitely dilute alloy of one metal in another via simultaneous strong electrostatic adsorption (co-SEA).

Previously, Wong et. al. [4] demonstrated the straightforward synthesis of silica supported, ultrasmall, homogeneously alloyed bimetallic catalyst at 1:1 atomic ratios by co-SEA. In the same manner, we extend the method to the dilution limit of one or two atoms in a crystallite of 30 or 40 atoms. The synthesis of various combinations of representative metals (Ru, Pd, Pt, Ni, Co, and Cu) on high surface area amorphous silica will be presented. Catalyst characterization will be carried out using high sensitivity powder x-ray diffraction, aberration-corrected electron microscopy, temperature programmed reduction, X-ray photoelectron spectroscopy and FTIR spectroscopy. Catalyst activity will be tested on reactions requiring high selectivity such as hydrodeoxygentation of biomass derived oxygenated hydrocarbon.

[1] J. Shan, J. Liu, M. Li, S. Lustig, S. Lee, and M. Flytzani-Stephanopoulos, “NiCu single atom alloys catalyze the CH bond activation in the selective non- oxidative ethanol dehydrogenation reaction,” Appl. Catal. B Environ., vol. 226, pp. 534–543, Jun. 2018.

[2] L. Zhang et al., “Efficient and durable Au alloyed Pd single-atom catalyst for the Ullmann reaction of aryl chlorides in water,” ACS Catal., vol. 4, no. 5, pp. 1546–1553, 2014.

[3] M. B. Boucher et al., “nanoparticles for selective hydrogenation reactions,” pp. 12187–12196, 2013.

[4] A. Wong, Q. Liu, S. Griffin, A. Nicholls, and J. R. Regalbuto, “Synthesis of ultrasmall, homogeneously alloyed, bimetallic nanoparticles on silica supports,” vol. 1430, no. December, pp. 1427–1430, 2017.